Certification Problem

Input (TPDB TRS_Outermost/Strategy_outermost_added_08/#4.18)

The rewrite relation of the following TRS is considered.

a(b(a(b(x)))) b(a(b(a(a(b(x)))))) (1)
The evaluation strategy is outermost

Property / Task

Prove or disprove termination.

Answer / Result

No.

Proof (by AProVE @ termCOMP 2023)

1 Loop

The following loop proves nontermination.

t0 = a(b(a(a(b(a(b(x')))))))
a(b(a(b(a(b(a(a(b(x')))))))))
b(a(b(a(a(b(a(b(a(a(b(x')))))))))))
= t2
where t2 = C[t0σ] and σ = {x'/a(a(b(x')))} and C = b()